# What You Need:
→ Chocolate & Cocoa
01 - 4 oz bittersweet chocolate, chopped
02 - 2 oz milk chocolate, chopped
03 - 1/4 cup unsweetened Dutch-process cocoa powder
→ Fats
04 - 1/2 cup unsalted butter, cubed
→ Sugar
05 - 1 cup granulated sugar
06 - 1/4 cup light brown sugar, packed
→ Sourdough & Liquids
07 - 1/2 cup sourdough discard, unfed
08 - 2 large eggs, room temperature
09 - 1 teaspoon pure vanilla extract
→ Dry Ingredients
10 - 2/3 cup all-purpose flour
11 - 1/2 teaspoon fine sea salt
→ Chocolate Mix-ins
12 - 1/3 cup semi-sweet chocolate chips or chunks
# Step-by-Step:
01 - Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper, allowing overhang for easy removal.
02 - Combine bittersweet chocolate, milk chocolate, cocoa powder, and butter in a heatproof bowl. Melt over simmering water or microwave in 30-second intervals, stirring until smooth. Allow to cool slightly.
03 - In a large bowl, whisk together sugars, eggs, and vanilla extract until pale and thick, approximately 2 to 3 minutes.
04 - Whisk sourdough discard into the cooled chocolate mixture until fully incorporated.
05 - Add the chocolate mixture to the egg-sugar mixture and gently mix until combined.
06 - Sift flour and salt into the batter. Fold in gently with a spatula until just combined; avoid overmixing.
07 - Gently fold in the semi-sweet chocolate chips or chunks until evenly distributed.
08 - Pour batter into the prepared pan and smooth the top with a spatula to ensure even baking.
09 - Bake for 28 to 32 minutes until edges are set and the center has a slight wobble. Avoid overbaking to maintain a chewy texture.
10 - Cool completely in the pan on a wire rack before lifting out and slicing into squares.